Bought one of those "USB Qi receivers" that look like a flattened plastic bag carrying a coil, as my phone doesn't support wireless charging natively. The phone charges now but only intermittently. Is there any way to get it to charge continously?

I don't use the wireless charger in the Car as I'm always plugged into USB for CarPlay, so only throwing out some suggestions! We have had an iPhone XR sitting on the wireless charger and not noticed any issues with the charging not being constant.

Does it work constantly if you sit it on a normal domestic wireless charge pad? That would at least identify if the USB coil thingy is defective.

Possibly the coils in the USB coil thingy are smaller than those in the phone, so more sensitive to positioning. If the phone slides slightly with the car motion it could be moving off the sweet spot.

I've tried both with & without the case. In both cases (pun not intended), the phone starts charging, followed by a faint sparking noise a few seconds later, at which point the phone stops & starts charging again.

I've ordered a USB wireless charging pad (the 'normal domestic' kind that morrishey mentioned) online, so hoping to have some clarity soon.

That doesn’t sound good. Can’t see that here’d be anything between car & charger that could cause an effect like that, it’s all electromagnetic, so I’d be very wary of the connection between charger and phone. You don’t want to be frying hundreds of £$ of phone for the sake of a dodgy charging solution.

That doesn’t sound good. Can’t see that here’d be anything between car & charger that could cause an effect like that, it’s all electromagnetic, so I’d be very wary of the connection between charger and phone. You don’t want to be frying hundreds of £$ of phone for the sake of a dodgy charging solution.

It sounds like you’re using a standard Qi charger, rather than Volvo’s built in one? If so, have you tried it in the house?

Haven't received the standard Qi charger yet... it's still in transit. I'll update when I receive it.

Sounds like your you are spending a lot of time,effort and money on getting a gadget to work that you don’t really need.
I assume the QI USB plastic bag thingy plugs into your phone’s power socket and charges it by induction between the car’s charger pad and the coil in the bag?. If so then any advantage of the “Wireless” charging goes out the window, you still have to plug the gadget into the phone so what’s the point. A lot easier and cheaper to use a short usb cable to connect the phone to the car usb socket....